FX803 Audio
Signalling Processor
SIGNAL INPUT BIAS
DIGITAL
NOISE
(Rx) AUDIO IN
INPUT
AMPLIFIER
V
DD
FILTER 1
Rx FILTER
SWITCH
DIGITAL
NOISE
FILTER 2
QUALITY
METER
PROGRAMABLE
NOTONE
TIMER
COMMAND DATA
REPLY DATA
C-BUS
INTERFACE
CHIP SELECT
AND
CONTROL
LOGIC
INTERRUPT
SERIAL CLOCK
LOGIC INPUT
GATE TIME
GENERATOR
FREQUENCY
COUNTER
PROGRAMABLE
(Tx PERIOD)
TIMER
V
BIAS
TONE 1
GENERATOR
5- / 2-TONE
DTMF 1
LOW
PASS
FILTER
TONE 1 OUT
SUM IN
SWITCHED SUM OUT
V
SS
SUMMING
SWITCH
CAL/CUES
SWITCH
SUM OUT
CAL/CUES OUT
V
BIAS
XTAL/CLOCK
CLOCK
GENERATOR
XTAL
AUDIO SWITCH IN
AUDIO SWITCH
CUES
SUMMING
AMPLIFIER
TONE 2
GENERATOR
CUES / DTMF 2
CAL
LOW
PASS
FILTER
TONE 2 OUT
AUDIO SWITCH OUT
Fig.1 FX803 Audio Signalling Processor
FX803 Audio Signalling Processor
As part of the DBS 800 System, this audio signalling
processor will provide an inband tone signalling facility for
PMR radio systems. Signalling systems supported include
Selcall (CCIR, ZVEI I, II and III, EEA), 2-Tone Selcall and
Dual Tone Multi-Frequency (DTMF) encode.
Using a non-predictive tone decoder and versatile
encoders gives the FX803 the capability to work in any
standard or non-standard tone system.
This is a full-duplex device consisting of:
q
q
q
Two individual tone generators and a
programmable (Tx) period timer.
A tone decoder with programmable N
OTONE
Timer.
An on-chip summing amplifier.
Both tone generators can be individually placed into a
power economical “Powersave” mode.
A general purpose logic input, interfacing directly with the
Status Register, is provided. This could be used as an
auxiliary method of routeing digital information to the
µController
via the “C-BUS.”
The output frequencies are produced from data loaded to
the device, with a programmable, general purpose, on-chip
timer available to indicate the tone transmit periods.
A Dual Tone Multi-Frequency (DTMF) output is obtained
by combining the 2 independent output frequencies in the
integral summing amplifier. This Summing Amplifier output
is also available for level adjustment.
Tones produced by the FX803 can also be used in the
DBS 800 system as modulation calibration inputs and for
“CUE” audio indications for the operator.
Received tones are measured and their frequency
indicated to the
µController
in the form of a received data
word. A poor-quality or incoherent tone will, after a
programmed period, indicate N
OTONE
.
The FX803 is a low-power, 5-volt CMOS integrated circuit
and is available in 24-pin DIL cerdip and 24-pin/lead plastic
SMD packages.
For use with Single Tone or Selective Call systems.
Under the control of the
µController,
via “C-BUS,” the
FX803 will encode and transmit a single or pair of audio
tones, in the frequency range 208Hz to 3kHz,
simultaneously, and detect, decode and indicate the
frequency of non-predicted input tones in the frequency
range 313Hz to 6kHz.
Publication D/803/6 April 1998
CMLMICRO [ CML MICROCIRCUITS ]
